Galaxy S4 Volume Fluctuations

Myobviousl fluctuates on my phone when playing videos or music and had had this issue since I got it in November. It's insured, so I can take it back, though. I can't figure out why it does this. I have heard that the phone has EQ issues, but I cannot find an EQ for the phone itself, only the music and video apps, and YouTube does it as well. Youtube doesn't have EQ settings that I can find.

It's rather annoying, especially when I have to turn the volume up in my car or headphones, then it gets super loud, nearly defeaning me (obviously not seriously).